A method for allocating total control flow with multiple imports and exports

Abstract

The present invention discloses a method for distributing flow from a multi-inlet and multi-outlet main pipe, comprising the following steps: constructing a multi-inlet and multi-outlet oil tank flow distribution system based on the main pipe; establishing an oil tank heating database and determining the opening of a dynamic flow regulating valve according to the actual conditions of the ship; the database includes the number of oil tanks, heating temperature, initial liquid level of the oil tank, resistance of the pipeline and equipment on the pipeline, head of the circulating oil pump, and changes in oil density before and after heat exchange; heating the oil tank according to the opening set by the dynamic flow regulating valve in the database, and revising the oil tank heating database according to the detected data during operation. The present invention ensures the feasibility and safety of heating multiple oil tanks through an oil tank heating monitoring automatic control module, and achieves similar inflow and outflow of oil when oil tanks at different distances from the main pipe are heated at the same time, thereby realizing the automatic control function of oil tank heating, improving the efficiency of heating multiple oil tanks, and reducing the workload and difficulty of crew members.

Description

Technical Field

[0001] The invention relates to a multi-inlet and multi-outlet master control flow distribution method, belonging to the field of oil tank heating. Background Art

[0002] When supply vessels, oil tankers and other ships are carrying high-viscosity oil products, such as diesel and other refined oils, this fluid is difficult to handle at room temperature due to its high viscosity. In order to ensure smooth unloading and replenishment, the cargo oil viscosity must be reduced by heating. Steam coils are usually used to increase the temperature of these liquids, reduce their viscosity and obtain a fluid with higher fluidity so that it can be pumped to the designated location.

[0003] like Figure 1 As shown, two steam pipelines 3 are connected to two oil pipelines 4 through a heat exchanger 2. Each oil pipeline 4 is connected to each oil tank 9. A fixed-frequency circulating oil pump 10 is provided on an oil pipeline 4 connected to the outlet of each oil tank 9. Another fixed-frequency circulating oil pump 10 is connected in parallel at both ends of the fixed-frequency circulating oil pump 10. The inlet of each oil tank 9 is connected to another oil pipeline 4 through a stop valve 6.

[0004] When it comes to heating multiple oil tanks under a multi-inlet and multi-outlet master control, there will be certain problems with the multi-inlet and multi-outlet master control form. When it comes to heating multiple oil tanks, there are generally two heating methods: one is to control the opening and closing of the inlet and outlet valves of the oil tanks, and heat the oil tanks one by one in a certain order. The advantage of this method is that there is no need to consider the hydraulic balance problem, and it is easier to achieve control in terms of reliability. However, the biggest disadvantage of this method is the low heating efficiency, and the circulating oil pump is in a low-load operation state for a long time, which is inefficient and increases the operating cost. In addition, cavitation is easily generated in the pump body, and the sealing is reduced, thereby reducing the service life of the circulating oil pump. The other method is to open the inlet and outlet valves of all oil tanks and heat the oil in the oil tanks at the same time. Although this method improves the heating efficiency of the oil tanks, due to the hydraulic characteristics of the pipe network, it causes hydraulic imbalance of the entire system. Hydraulic imbalance will bring two problems:

[0005] (1) Due to the differences in the hydraulic characteristics of the pipe network, the oil tanks closer to the main pipe have stronger hydraulic characteristics than those farther away, resulting in a greater difference in the oil flow rate entering and out of the tanks. This results in excessive oil in the tanks closer to the main pipe, exceeding the initial unheated liquid level and even overflowing from the tanks.

[0006] (2) Changes in the amount of oil in the tanks lead to inconsistent temperatures in the various tanks, resulting in overheating or underheating of a tank;

[0007] (3) The operating conditions of the oil tank heating system are constantly changing. For example, the change in the number of oil tanks that need to be heated causes the flow rate in the main pipe to change. The system needs to have a certain adjustment capability to achieve efficient and stable heating of the oil tanks under multiple working conditions.

[0008] Based on the above analysis, it can be seen that in order to ensure the efficient simultaneous heating of multiple oil tanks and to ensure that the heating temperatures of each oil tank are relatively consistent, it is necessary to construct a multi-inlet and multi-outlet total control flow distribution method to solve the problem of insufficient operation of existing resources and ensure the safe operation of the entire system. Summary of the Invention

[0009] The technical problem to be solved by the present invention is: how to ensure that multiple oil tanks are heated simultaneously with high efficiency and that the heating temperatures of the oil tanks are relatively consistent.

[0010] In order to solve the above technical problems, the technical solution of the present invention is to provide a method for allocating total control flow of multiple inlets and outlets, which is characterized by comprising the following steps:

[0011] Step 1: Construct a multi-inlet and multi-outlet oil tank flow distribution system based on master control: The flow distribution system includes

[0012] Power module, providing power for the entire oil circulation heating;

[0013] The heat exchange module provides heat source for heating the oil tank module, ensuring that the oil in the oil tank module is heated to the set temperature;

[0014] The oil tank module is a large space compartment for storing oil. The oil tank module includes multiple oil tanks;

[0015] Pipeline module is the pipeline system connecting various modules;

[0016] Monitoring automatic control module to ensure that the total amount of oil in each tank remains unchanged before and after heating;

[0017] The input end of the power module is connected to the oil tank module through the pipeline module, the output end of the power module is connected to the input end of the heat exchange module, and the output end of the heat exchange module is connected to the pipeline module;

[0018] Step 2: Based on the actual conditions of the ship, establish an oil tank heating database and determine the dynamic flow control valve opening; the database includes the number of oil tanks, heating temperature, initial oil tank level, pipeline and equipment resistance on the pipeline, circulating oil pump head, and oil density changes before and after heat exchange;

[0019] Step 3: Heat the oil tank according to the opening set by the dynamic flow control valve in the database, and modify the oil tank heating database according to the detected data during operation.

[0020] Preferably, the power module is one or more circulating oil pumps, the input end of the circulating oil pump is connected to the oil main pipe, and the output end of the circulating oil pump is connected to the heat exchange module; the heat exchange module is a heat exchanger, the input end of the heat exchanger is connected to the circulating oil pump, the circulating oil pump transports the oil in the oil tank to the heat exchanger, and the output end of the heat exchanger is connected to the oil main pipe; according to the number of oil tanks, the pipeline module is divided into multiple branches, and each branch pipe converges into a main pipe, and continuously circulates under the power provided by the power module.

[0021] Preferably, the monitoring automatic control module includes pressure monitoring equipment arranged at the inlet and outlet of the oil tank, and a flow meter and a dynamic flow regulating valve arranged on the branch pipe entering the oil tank.

[0022] Preferably, the steps for correcting the oil tank heating database are as follows: select several typical heating conditions, perform operational debugging, debug the dynamic flow control valve, use the pressure gauges and inlet flow meters at the oil tank inlet and outlet, and measure the pressure and flow data under the conditions of simultaneous heating of different numbers of oil tanks; calculate the relationship between pressure loss and actual flow based on the measurement results, and correct the resistance loss curve under the database simulation state.

[0023] Preferably, the monitoring automatic control module further comprises a liquid level monitoring device provided inside the oil tank; in order to ensure that the oil tank liquid level is at a safe level when the dynamic flow regulating valve fails to regulate, a liquid level monitoring device is provided in each oil tank, and the monitoring liquid level index is Z * , when the liquid level reaches Z * The alarm starts and the heating of the oil tank is stopped.

[0024] Preferably, according to the oil tank module parameters, the number of oil tanks is N, and the ship oil tanks are numbered and represented as O1, O2, ..., O i ,…,O N Where N≥2; Determine the time required to heat an oil tank, and determine the oil tank inlet branch flow rate Q based on the time requirement; The initial liquid level of each oil tank: Z1, Z2, ..., Z i ,…,Z N Where N≥2; before and after the heat exchange module, the density of the oil will change after heating. The corresponding density value is found according to the heating temperature T. The density change of the oil before and after heating is Δρ; due to the change in density of the oil before and after heating, if the total mass of the oil tank remains unchanged before and after heating, the liquid level of the oil tank will change. The liquid level of the oil tank after heating is Z * , Z * =f(Δρ,Z).

[0025] Preferably, the oil tank heating has multiple working conditions. According to the number of oil tank heating conditions, there are M possible working conditions in total.

[0026] Preferably, the pipeline model is established by using FLOWMASTER to perform fluid calculation analysis under all possible working conditions of oil tank heating.

[0027] Preferably, the circulating oil pump adopts a variable frequency circulating oil pump, and the head H of the circulating oil pump changes according to the change of the delivery flow rate; due to the change in the number of heating oil tanks, the flow rate in the same pipeline main changes, the pipeline resistance Σδ will also change accordingly, and a resistance loss curve is drawn.

[0028] Preferably, the flow of oil entering the oil tank is controlled by a dynamic flow regulating valve, and the opening of the dynamic flow regulating valve is adjusted with Q as the target flow; the opening of the dynamic flow regulating valve at a certain oil tank inlet P i Is related to the oil tank level Z * , circulating oil pump head H, pipeline resistance ∑δ factors are closely related, so P i =f(Z * ,H,∑δ)=f(Δρ,Z,H,∑δ).

[0029] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0030] 1. The present invention ensures the feasibility and safety of heating multiple oil tanks through the oil tank heating monitoring automatic control module.

[0031] 2. The present invention uses the oil tank heating monitoring automatic control module to ensure that the oil flow rates entering and outflowing from oil tanks at different distances from the main pipe are similar when heating at the same time.

[0032] 3. Ensure that the heating temperature of each oil tank is consistent, solving the problem of overheating or insufficient heating in traditional oil tank heating.

[0033] 4. The present invention realizes the automatic control function of oil tank heating through the oil tank heating monitoring automatic control module, improves the efficiency of heating multiple oil tanks, and reduces the workload and difficulty of crew members. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a heating principle diagram of the general control mode of the oil tank heating system in the prior art;

[0035] Figure 2 A heating principle diagram of a multi-inlet and multi-outlet total control flow distribution method provided by the present invention;

[0036] Figure 3 The present invention provides a flowchart of a method for distributing total control flow with multiple imports and exports. DETAILED DESCRIPTION

[0037] To make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0038] The present invention provides a multi-inlet and multi-outlet total control flow distribution method in an oil tank heating system, such as Figure 2 As shown, it includes the following steps:

[0039] First, a multi-inlet and multi-outlet oil tank flow distribution system based on master control is constructed:

[0040] The system includes a power module, a heat exchange module, an oil tank module, a pipeline module and a monitoring and automatic control module;

[0041] The power module provides power for the circulation heating of the entire oil, which can be one or more circulating oil pumps. In this embodiment, there are two variable frequency circulating oil pumps 1. The input end of the circulating oil pump is connected to the oil main pipe, and the output end of the circulating oil pump is a heat exchange module; the heat exchange module provides a heat source for heating the oil tank 9 to ensure that the oil in the oil tank 9 is heated to a set temperature. In this embodiment, it is a heat exchanger 2 with steam as the heat source. The input end of the heat exchanger 2 is connected to the circulating oil pump, and the circulating oil pump transports the oil in the oil tank 9 to the heat exchanger 2. The output end of the heat exchanger 2 is connected to the oil main pipe; the oil tank module is a large The volume and number of the space compartments and the oil tanks 9 are determined according to the actual design of the ship. In this embodiment, there are three oil tanks 9. The pipeline module is a pipeline system connecting each module. It is divided into multiple branches according to the number of oil tanks 9. Each branch pipe converges into a main pipe and circulates continuously under the power provided by the power module. The monitoring automatic control module ensures that the total amount of oil in each oil tank 9 remains unchanged before and after heating. Pressure monitoring equipment is set at the inlet and outlet of the oil tank 9, a flow meter 8 and a dynamic flow regulating valve 7 are set on the branch pipe entering the oil tank 9, and a liquid level monitoring device is set inside the oil tank 9.

[0042] In this embodiment, two steam pipelines 3 are connected to two oil pipelines 4 through a heat exchanger 2. Each oil pipeline 4 is connected to each oil tank 9 respectively. A variable frequency circulating oil pump 1 is provided on an oil pipeline 4 connected to the outlet of each oil tank 9. Another variable frequency circulating oil pump 1 is connected in parallel at both ends of the variable frequency circulating oil pump 1. The inlet of each oil tank 9 is connected to another oil pipeline 4 through a stop valve 6. A dynamic flow regulating valve 7 is provided on the pipeline where the stop valve 6 is located and between the stop valve 6 and the oil tank 9. A flow meter 8 is provided between the dynamic flow regulating valve 7 and the oil tank 9. A pressure gauge 5 is provided on the pipeline where the stop valve 6 is located and at the end of the stop valve 6 away from the oil tank 9.

[0043] During the whole process of implementing the heating task of oil tank 9, usually Figure 3 The specific steps for implementing the process shown are as follows:

[0044] According to the actual situation of the ship, an oil tank heating database is established. The database includes: at the beginning of the ship design, the heating requirements of the oil tank 9 (including the number of oil tanks 9, heating temperature, etc.), the initial liquid level of the oil tank 9, the resistance of the pipeline and the equipment on the pipeline, the head of the circulating oil pump, the change in oil density before and after heat exchange, etc.; according to the oil tank module parameters, the number of oil tanks 9 is 3, and the ship's oil tanks 9 are numbered and represented as O1, O2, and O3 respectively; based on the ship's heating requirements, the selection of circulating oil pumps, economic efficiency and other considerations, the time required to heat an oil tank 9 will be determined, and the oil tank 9 inlet branch flow Q can be determined according to the time requirement; the initial liquid level of each oil tank 9: Z1, Z2, Z3; before and after the heat exchanger 2, after heating, the density of the oil will change, and the corresponding density value can be found according to the heating temperature T. The change in oil density before and after heating is Δρ; due to the change in oil density before and after heating, if the total mass of the oil tank 9 before and after heating remains unchanged, the liquid level of the oil tank 9 will change, and the liquid level of the oil tank 9 after heating is Z * , Z * =f(Δρ,Z).

[0045] There are many working conditions for heating the oil tank 9. According to the number of oil tanks 9 to be heated, the formula It can be calculated that there are 4 types of working conditions for heating more than 2 oil tanks 9. The circulating oil pump adopts a variable frequency circulating oil pump 1, and the head H of the circulating oil pump changes according to the change of the delivery flow rate; the pipeline model is established by using FLOWMASTER, and the fluid calculation analysis of the 4 working conditions of heating the oil tank 9 can be performed. Due to the change in the number of heated oil tanks 9, the flow in the same pipeline main pipe changes. The pipeline resistance ∑δ under the 4 working conditions is calculated and the resistance loss curve under different working conditions is drawn. Corresponding to the resistance of the 4 different working conditions, the head H of the variable frequency circulating oil pump 1 is determined accordingly; the flow of oil entering the oil tank 9 is controlled by the dynamic flow control valve 7, and the opening of the dynamic flow control valve 7 is adjusted with Q as the target flow rate; the opening P of the dynamic flow control valve 7 at the inlet of a certain oil tank 9 i Is related to the oil tank 9 level Z * , circulating oil pump head H, pipeline resistance ∑δ and other factors are closely related. According to the formula P i =f(Z * ,H,∑δ)=f(Δρ,Z,H,∑δ), the opening of the dynamic flow control valve 7 of the heating oil tank 9 under the four working conditions can be calculated.

[0046] According to the actual task requirements, a certain heating condition is selected and the oil tank 9 is heated according to the opening set by the dynamic flow control valve 7 in the database. During operation, the oil tank heating database is corrected according to the detected pressure, flow and other data:

[0047] Several typical heating conditions were selected for operation debugging. The dynamic flow control valve 7 was debugged. The pressure gauges 5 at the inlet and outlet of the oil tanks 9 and the inlet flow meter 8 were used to measure the pressure and flow data under the conditions of simultaneous heating of different numbers of oil tanks 9. The relationship between pressure loss and actual flow was calculated based on the measurement results, and the resistance loss curve under the database simulation state was corrected.

[0048] In order to ensure that the liquid level of the oil tank 9 is at a safe level when the dynamic flow control valve 7 fails to adjust, a liquid level monitoring device 11 is set in each oil tank 9. The monitoring liquid level index is Z * , when the liquid level reaches Z * When the alarm is started, the heating of the oil tank 9 is stopped.

Claims

1. A method for allocating total flow rate of multi-inlet and multi-outlet control, characterized in that: The following steps are involved: Step 1: Construct a multi-inlet and multi-outlet oil tank flow distribution system based on master control: The flow distribution system includes Power module, providing power for the entire oil circulation heating; The heat exchange module provides heat source for heating the oil tank module, ensuring that the oil in the oil tank module is heated to the set temperature; The oil tank module is a large space compartment for storing oil, and the oil tank module includes multiple oil tanks (9); Pipeline module is the pipeline system connecting various modules; Monitoring the automatic control module to ensure that the total amount of oil in each oil tank (9) remains unchanged before and after heating; The input end of the power module is connected to the oil tank module through the pipeline module, the output end of the power module is connected to the input end of the heat exchange module, and the output end of the heat exchange module is connected to the pipeline module; Step 2: Based on the actual situation of the ship, establish an oil tank heating database and determine the opening of the dynamic flow control valve (7); the database includes the number of oil tanks (9), heating temperature, initial liquid level of the oil tank (9), resistance of pipelines and equipment on the pipelines, head of the circulating oil pump, and changes in oil density before and after heat exchange; Step 3: Heat the oil tank (9) according to the opening set by the dynamic flow control valve (7) in the database, and modify the oil tank heating database according to the detected data during operation.

2. A method for allocating total flow rate of multiple inlets and outlets according to claim 1, characterized in that: The power module is one or more circulating oil pumps, the input end of the circulating oil pump is connected to the oil main pipe, and the output end of the circulating oil pump is connected to the heat exchange module; the heat exchange module is a heat exchanger (2), the input end of the heat exchanger (2) is connected to the circulating oil pump, the circulating oil pump transports the oil in the oil tank (9) to the heat exchanger (2), and the output end of the heat exchanger (2) is connected to the oil main pipe; according to the number of oil tanks (9), the pipeline module is divided into multiple branches, and each branch pipe is connected to a main pipe, and continuously circulates under the power provided by the power module.

3. A method for allocating total flow rate of multi-inlet and multi-outlet control according to claim 1, characterized in that: The monitoring automatic control module comprises pressure monitoring equipment arranged at the inlet and outlet of the oil tank (9), a flow meter (8) and a dynamic flow regulating valve (7) arranged on a branch pipe entering the oil tank (9).

4. A method for allocating total flow rate of multi-inlet and multi-outlet control according to claim 3, characterized in that: The steps of correcting the oil tank heating database are as follows: selecting several typical heating conditions, performing operation debugging, debugging the dynamic flow control valve (7), using the pressure gauges (5) at the inlet and outlet of the oil tank (9) and the inlet flow meter (8), measuring the pressure and flow data under the simultaneous heating conditions of different numbers of oil tanks (9); calculating the relationship between the pressure loss and the actual flow based on the measurement results, and correcting the resistance loss curve under the database simulation state.

5. A method for allocating total flow rate of multi-inlet and multi-outlet control according to claim 3, characterized in that: The monitoring automatic control module further includes a liquid level monitoring device provided inside the oil tank (9); in order to ensure that the liquid level of the oil tank (9) is at a safe level when the dynamic flow regulating valve (7) fails to adjust, a liquid level monitoring device (11) is provided in each oil tank (9), and the monitoring liquid level index is Z * , when the liquid level reaches Z * When the alarm is started, heating of the oil tank (9) is stopped.

6. A method for allocating total flow rate of multi-inlet and multi-outlet control according to claim 1, characterized in that: According to the oil tank module parameters, the number of oil tanks (9) is N, and the ship oil tanks (9) are numbered and represented as O1, O2, ..., O i ,…,O N ; Wherein, N≥2; Determine the time required to heat an oil tank (9), and determine the oil tank (9) inlet branch flow rate Q according to the time requirement; The initial liquid level of each oil tank (9): Z1, Z2, ..., Z i ,…,Z N Wherein, N≥2; before and after the heat exchange module, after heating, the density of the oil will change, and the corresponding density value is found according to the heating temperature T. The density change of the oil before and after heating is Δρ; due to the change in the density of the oil before and after heating, if the total mass of the oil tank (9) before and after heating remains unchanged, the liquid level of the oil tank (9) changes, and the liquid level of the oil tank (9) after heating is Z * , Z * =f(Δρ, Z).

7. A method for allocating total flow rate of multi-inlet and multi-outlet control according to claim 6, characterized in that: There are multiple working conditions for heating the oil tank (9). According to the number of heated oil tanks (9), there are M possible working conditions in total.

8. A method for allocating total flow rate of multi-inlet and multi-outlet control according to claim 7, characterized in that: A pipeline model is established using FLOWMASTER, and fluid calculation analysis is performed on all possible working conditions of heating the oil tank (9).

9. A method for allocating total flow rate of multi-inlet and multi-outlet control according to claim 6, characterized in that: The circulating oil pump adopts a variable frequency circulating oil pump (1), and the head H of the circulating oil pump changes according to the change of the conveying flow rate; since the number of heating oil tanks (9) changes, the flow rate in the same pipeline main changes, and the pipeline resistance Σδ also changes accordingly, and a resistance loss curve is drawn.

10. A method for allocating total flow rate of multi-inlet and multi-outlet control according to claim 6, characterized in that: The flow of oil entering the oil tank (9) is controlled by a dynamic flow regulating valve (7), and the opening of the dynamic flow regulating valve (7) is adjusted with Q as the target flow; the opening P of the dynamic flow regulating valve (7) at the inlet of a certain oil tank (9) is i Is related to the oil tank (9) liquid level Z * , circulating oil pump head H, pipeline resistance ∑δ factors are closely related, so P i =f(Z * ,H,Σδ)=f(Δρ,Z,H,Σδ).

Images